In the conventional manufacturing line for battery, the batteries are assembled, followed by processes such as charging/discharging, storage, performance test, and shipment as products.
For example, in the charging process, the program controls the charge condition to the proper extent. In the process, the fault of the charging program results in overcharge of the battery, and the chain reaction in the battery rapidly occurs, thereby causing the abnormal rise in temperature of the battery. In the other processes, the short circuit caused by the defective battery or the heat added from outside may cause abnormal rise in temperature of the battery.
The abnormal temperature rising may occur thermorunaway of the battery, so that various techniques are provided to detect the abnormality of the battery in the conventional line.
Patent Literature 1 discloses a charge/discharge apparatus for charging and discharging batteries, in which every battery housed in a casing is arranged with a temperature sensor, and the apparatus includes a facility that stops the charging in accordance with the detected temperature by means of the temperature sensor and an alarm device alerting in accordance with the detected temperature. The apparatus is allowed to detect the abnormal temperature rising by means of the temperature sensors and to prevent the thermorunaway caused by the abnormal temperature rising.
Unfortunately, as to the abnormality detection facility disclosed in the Patent Literature 1, every battery in the casing has to be attached with the temperature sensor, or each battery has to be arranged in the predetermined position on which the temperature sensor is mounted. Thus, the facility of the Patent Literature 1 includes disadvantages that the attaching operation of the temperature sensors to the batteries or the arranging operation of the batteries is troublesome.
When the facility of the Patent Literature 1 is applied to a large-scale facility for manufacturing a large number of batteries, it is not practical to prepare the temperature sensors by the same number as the batteries and to monitor the temperatures of each battery, considering the attaching operation, the monitoring operation, and the cost of equipment.
Furthermore, the detectable area of the sensor is limited to the portion where the detecting unit contacts, and a large number of sensors are needed to provide a wide area monitoring for the batteries, such as to widely detect the temperature of the battery surfaces, whereby the structure is not practical.    [Patent Literature 1] JP H11-219732 A